1. Field of the Invention
The present invention relates generally to placer mining machinery, and more particularly to devices for separating heavy minerals from aggregate material.
2. Related Art
Small volumes of valuable minerals may be present in naturally occurring aggregate materials, and also in processed ore, or tailings, from mining processes such as dredging, dry washing, sluicing, and trammeling. Recovery of the small volume of minerals from such placer ore has had little if any commercial value because of the large recovery cost in manpower, equipment time, etc. as compared to the value of the minerals. Various types of devices have been developed to try to recover precious metals, minerals and gemstones from these natural or processed aggregate placer ores.
One of the oldest types of equipment used is the sluice. In a sluice, aggregate materials are mixed with water in an inclined trough or flume where heavy particles such as gold, diamonds, etc. sink to the bottom of the trough where they can be recovered. One problem with sluice separators is that they are unable to separate and recover very fine mineral particles, such as black sand and gold flour, from mineral bearing placer ore.
Other devices have been developed that attempt to use the specific gravity of various minerals to separate out the heavier minerals from the placer ore. These devices have had problems keeping the extremely fine particulates of the heavier minerals from being washed away with the discarded aggregate material.